TCF6000 Datasheet, PDF (3/6 Pages) Motorola, Inc – PERIPHERAL CLAMPING ARRAY

Figure 3. Clamping Characteristics
IIK
+10 mA
–0.3 V 0 V
VCC
Vin
VCC+
0.75 V Typ
Low
Impedance
–10 mA
High
Impedance
Low
Impedance
TCF6000
APPLICATIONS INFORMATION
Figure 4 depicts a typical application in a microcomputer
based automotive ignition system.
The TCF6000 is being used not only to protect the
system’s normal inputs but also the (bidirectional) serial
diagnostics port.
The value of the input resistors, Rin, is determined by the
clamping current and the anticipated value of the spikes.
Thus:
Rin =
V
IIK
Ω
where: V = Peak Volts (V)
IIK = Clamping current (A)
So, taking, V = 300 V typically (SAE J1211)
gives,
IIK = 10 mA (recommended)
Rin= 30 k
Resistors of this value will not usually cause any problems
in MOS systems, but their presence needs to be taken into
account by the designer. Their effect will normally need to be
compensated for Bipolar systems.
Figure 4. Typical Automotive Application
VCC
Gnd
Vbat
Vbat
Hall
Effect
Pick Up
Engine
Temperature
RHall
Pressure
Sensor
Gnd
Battery
Volts
Gnd
6X
Rin
3X
Cin
Gnd
VCC
INT1
B0
D1
D6
MC6805S2
D0
B1
D2
B2
VSS
Gnd
Serial Diagnostics
Car
Ignition Module
Coil Drive
Coil Feedback
MOTOROLA ANALOG IC DEVICE DATA
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